Traditionally, when manufacturing displays, such as plasma display panels (PDP) and liquid crystal displays (LCD), the displays generally can not provide a sufficient uniformity of the illuminating ratio of three primary colors, i.e. red, green, and blue. As a result, display manufacturers can not ensure that each of the manufactured displays can exhibit optimal color performances even though the displays in the same batch are manufactured by the same manufacturer, and with the same process. Thus, after the displays are manufactured, the grayscale/white balance of the displays will be adjusted by the manufacturer before outputting final products. Presently, the typical adjusting method comprises the following steps: detecting the color temperature and the color deviation of the display by a detector during the display displays a white color; and manually adjusting gain values of the three colors of red, green, and blue until the white color of the display is close to a predetermined range of the color temperature and the color deviation. Accordingly, the manufactured displays will be adjusted to exhibit a relatively correct grayscale/white balance with optimal color performances. However, the step of manually adjusting parameters of the grayscale/white balance needs more manufacturing time and manual labor while it is easy to cause manual deviation during manual adjusting. Thereby, a considerable difference is inevitably existed between actual parameters of the grayscale/white balance of the display and the predetermined parameter range thereof so as to relatively reduce the uniformity of final product quality.
Furthermore, conventionally, for lowering the cost of manufacture time and manual labor and speeding parameter adjustment of grayscale/white balance, display manufacturers generally select one display per batch to adjust its parameter of grayscale/white balance so as to obtain gain values of its three primary colors of red, green, and blue, which are used as a benchmark for determining gain values of other displays in the same batch and adjusting parameters of grayscale/white balance thereof. Briefly, gain values of all displays in the same batch are adjusted to the same fixed values in order to save considerable cost of manufacturing time and manual labor and to speed parameter adjustment of grayscale/white balance of the displays. However, differences of color performances between each of the displays are not considered so as to lower actual color performances of most displays. In fact, only one display, i.e. the selected one, can exhibit optimal color performances, and other displays can not exhibit optimal color performances at all.